On 12/16/19 10:38 AM, Waiman Long wrote: > On 12/16/19 8:26 AM, Michal Hocko wrote: >> On Thu 12-12-19 15:52:20, Waiman Long wrote: >>> On 12/12/19 2:22 PM, Mike Kravetz wrote: >>>> On 12/12/19 11:04 AM, Davidlohr Bueso wrote: >>>>> There have been deadlock reports[1, 2] where put_page is called >>>>> from softirq context and this causes trouble with the hugetlb_lock, >>>>> as well as potentially the subpool lock. >>>>> >>>>> For such an unlikely scenario, lets not add irq dancing overhead >>>>> to the lock+unlock operations, which could incur in expensive >>>>> instruction dependencies, particularly when considering hard-irq >>>>> safety. For example PUSHF+POPF on x86. >>>>> >>>>> Instead, just use a workqueue and do the free_huge_page() in regular >>>>> task context. >>>>> >>>>> [1] https://lore.kernel.org/lkml/20191211194615.18502-1-longman@xxxxxxxxxx/ >>>>> [2] https://lore.kernel.org/lkml/20180905112341.21355-1-aneesh.kumar@xxxxxxxxxxxxx/ >>>>> >>>>> Reported-by: Waiman Long <longman@xxxxxxxxxx> >>>>> Reported-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx> >>>>> Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx> >>>> Thank you Davidlohr. >>>> >>>> The patch does seem fairly simple and straight forward. I need to brush up >>>> on my workqueue knowledge to provide a full review. >>>> >>>> Longman, >>>> Do you have a test to reproduce the issue? If so, can you try running with >>>> this patch. >>> Yes, I do have a test that can reproduce the issue. I will run it with >>> the patch and report the status tomorrow. >> Can you extract guts of the testcase and integrate them into hugetlb >> test suite? BTW, what hugetlb test suite are you talking about? Cheers, Longman
